Apparatus has previously been known for use in connection with wrapping packages in thermoplastic film material which apparatus permitted the manual withdrawal of such film from a continuous roll thereof, facilitated the wrapping thereof partially around the package, severing the wrapped portion from the roll and finally facilitated the completion of the manual wrapping operation and heat sealing of the wrapped package. An example of such a machine is illustrated and described in detail in the patent to Pizmoht, U.S. Pat. No. 3,724,167.
This device, however, in common with many others currently utilized for such wrapping procedures, employs a hot wire for effecting the severing of the film wrapped at a given moment around a package from a continuous roll thereof. This operates satisfactorily but evidence has accumulated suggesting a possible harmful effect on the operator from the use of the hot wire. This is particularly true where the film is of polyvinyl chloride such that the hot wire releases small quantities of HCl gas. It is accordingly desirable to eliminate from the procedure in question the step of severing such film with a hot wire and to replace same with mechanical means by which such gas is not released.
There is, however, a very large number of machines, as aforesaid, already in use and their complete redesign and replacement would be an extremely expensive undertaking. Further, large numbers of operators have been trained in the use of these machines and the particular manual manipulations required by them have been carefully worked out for maximum efficiency over a long period of time. It is therefore desirable that the conversion be made by an adapter which would merely eliminate the hot wire and preserve as much of the original machine as possible and further that such adapter operate in conjunction with the rest of the machine in such a manner as to preserve the sequence of manual manipulations previously used for such previously known machines, such as the machine represented by the above-mentioned patent.
Accordingly, the objects of the invention include:
1. To provide an adapter for utilization with a machine such as that represented by the U.S. patent to Pizmoht, U.S. Pat. No. 3,724,167, whereby the severing of the film material by a hot wire is eliminated and the severing function is performed by mechanical means.
2. To provide apparatus, as aforesaid, comprising an adapter compatible with said previously known machine which will require only easily made modifications of the original machine to enable same to receive and cooperate with said adapter.
3. To provide apparatus, as aforesaid, which in its normal mode of use will not appreciably if any change the sequence of manual manipulations already known and utilized in the operation of the presently known machines.
4. To provide apparatus, as aforesaid, which will be of relatively simple construction and hence inexpensive to manufacture and easy to maintain in good operating condition.
5. To provide apparatus, as aforesaid, which in spite of its dependency upon a relatively moving knife and knife bed assembly will have a high safety factor with respect to the operator.